California faces heightened risks from aging dams as the state prepares for a potentially heavy El Niño winter, according to a recent state audit. The report, released Monday, highlights ongoing concerns about the structural condition and maintenance of many dams, particularly those near densely populated coastal regions such as the Bay Area, San Diego, and Los Angeles.
The audit found that 57 dams were in poor or unsatisfactory condition as of May, an increase from previous evaluations. Among these, 40 are classified as high or extremely high hazard dams, meaning their failure could lead to significant loss of life and economic damage. The report estimates that a collapse of these dams could endanger up to 1.5 million people and cause more than $265 billion in property damages.
California’s Department of Water Resources (DWR) oversees safety for over 1,220 dams, with maintenance responsibilities falling primarily on local governments, utilities, water agencies, private landowners, and companies. Several dams in poor condition are owned by state agencies. The department has the authority to impose penalties on dam owners who fail to meet safety standards, including reservoir restrictions, fines, and property liens—a power granted by lawmakers in 2017 following the Oroville Dam spillway failure that led to the evacuation of nearly 200,000 residents.
Despite this authority, the audit notes that the DWR has yet to take punitive enforcement actions against dam owners referred for violations. Since April, owners of 44 dams have been referred for enforcement, but the agency cites challenges in staffing and concerns about the potential costs of defending enforcement actions in hearings. The audit also warns of a gap in state law that prevents authorities from acting until a dam poses an emergency-level danger, leaving public safety vulnerable.
Many of California’s dams are aging, with some built under outdated safety standards. The state does not require dam owners to set aside dedicated funds for repairs, resulting in financial barriers to necessary maintenance. The audit highlights examples of long-standing issues, including a dam with a 47-foot-wide hole in its spillway that has remained unrepaired for over 30 years, posing flood risks to hundreds of people and risking tens of millions in damages.
Funding for dam repair has fluctuated in recent years. While Governor Gavin Newsom emphasized dam repairs as part of drought response efforts four years ago, state funding for repair grants was cut in 2024. However, a 2024 ballot measure provided a $464 million boost to the program, supplemented recently by a federal grant of approximately $629,000. Still, the audit estimates that repairing dams in poor or unsatisfactory condition could cost around $28 billion, vastly outweighing available resources.
The report calls on state lawmakers to establish firm deadlines and require dam owners with high-hazard dams to submit comprehensive maintenance and repair plans. It also urges expanding enforcement powers to allow the DWR to order the condemnation and decommissioning of dams if owners fail to address serious deficiencies.
Laura Hollender, deputy director of flood management and safety with the DWR, said the department is reviewing the audit’s recommendations but disagrees with some findings. She emphasized that public safety remains the department’s top priority and that preparations are underway for the upcoming wet season.
Additionally, the audit points to incomplete dam safety planning statewide. Emergency plans for 245 dams have not yet received approval from the Governor’s Office of Emergency Services, with officials attributing the delay to dam owners’ incomplete revisions and the absence of statutory deadlines.